Miguel Garcia-Garibay tells Joanne Thomson how he is pushing the limits of chemical reactivity to make molecular machines.

Miguel Garcia-Garibay is a member of the Department of Chemistry and Biochemistry and the California NanoSystems Institute of the University of California, Los Angeles, US. He has achieved international reputation for his work in solid-state organic chemistry, which includes photochemical reaction mechanisms, green chemical synthesis and artificial molecular machinery.

What inspired you to become a chemist? 

I was fortunate to have discovered early on that chemistry is rewarding and fun. When I was a high school student in Mexico, I had the opportunity to work as a lab helper. I had a few relatively trivial tasks such as 'babysitting' distillations and collecting column chromatography fractions. While these tasks may seem incredibly boring, having the means to do some freelance experiments provided me with huge amounts of entertainment. When hours in the lab felt like minutes, I knew that I wanted to do science for a living. Being a research chemist and a teacher has never felt like a job to me.  

You are interested in engineering motion in crystals. Why did you decide to focus on this area? 

To think about molecular motion and crystalline solids in the same context is so counterintuitive that it almost feels oxymoronic. The idea of engineering motion in solids did not a come in a 'Eureka!' moment but rather as the logical result of the many questions asked by a research group that was trying to understand reactions in crystals. In the mid 1990s, our group set out to push the limits of chemical reactivity under conditions where most of the thermal energy has been removed from the reactant and its medium. After all, if most of the universe is at a few Kelvin, one must wonder what sorts of chemical reactions are possible there. Using a hydrogen atom transfer reaction as a model, we were able to show that reactions in crystals can take place in a predictable manner, even at 4 K, as long as the structure is conducive to quantum mechanical tunnelling. We were able to draw some structure-reactivity correlations for quantum mechanical tunnelling, and to determine some of the largest isotope effects known to date. Perhaps boldened by the fact that we could design crystals where reactions could not be stopped even at a few degrees away from 0 K, we asked ourselves whether we could engineer crystals where some components could exists in a state of motion that is as fast as the one they would have in the gas phase. While trying to put such hypothetical crystals in the same context as other forms of condensed phase matter, such as liquids, liquid crystals and plastic crystals, we identified a new class of 'amphidynamic' crystals. As the name suggests, amphidynamic crystals occupy the region of the phase diagram where components coexist at the two ends of the dynamic spectrum: some structural elements are static at their lattice sites and others experience very fast, large amplitude motions. To design amphidynamic crystals one must think about using frames, pivots, axles, rotors, blades and so on, which naturally brought us into the exciting realm of molecular machinery. Amphidynamic crystals are densely packed structures with components that experience individual and collective degrees of freedom, just like complex macroscopic machines. We believe that crystalline molecular machines can be designed with extended lattices and discrete molecular solids such as those formed by metal-organic frameworks and molecular gyroscopes. 

What sort of tasks can molecular machines be used for? 

Taking hints from biology, we can speculate that combinations of artificial molecular machines will be able to do just about any task that a living organism can do now, and then some. While still far from complex molecular machinery, chemists have made enormous progress in the design and understanding of some simple machine components as well as some of their mechanical and electronic processes. However, as a solid-state organic chemist, I feel that the closest forms of serviceable molecular machinery will be in the form of smart and functional materials. We know that relatively simple chemical processes can have a deep influence over the physical properties of solids and we know that we have the means to control several chemical and mechanical phenomena. I speculate that the first fully artificial molecular machines will take the form of switches, sensors, displays and other communication technology devices. While their function will be based on controllable processes that take place at the molecular level, their properties will be manifested at the macroscopic scale. 

What else are you working on at the moment? 

In addition to studies in the field of crystalline molecular machinery, my group is developing chemical processes in crystalline solids for the synthesis of complex molecules. We have ongoing efforts on a very robust method for the synthesis of structures with all-carbon adjacent stereogenic quaternary centres. We are also working on the development of nanocrystalline photocatalysts and reactions on atomically smooth surfaces to prepare user-defined nanopatterns. Most of our work addresses the basic science and applications of organic chemistry in the solid state. 

You joined the Organic & Biomolecular Chemistry editorial board earlier this year. What do you enjoy most about your role? 

I admire the strong commitment that the staff and board members have to serve the organic and bioorganic chemistry community. I really enjoy being part of a group that aims at the highest standards of scientific publishing by encouraging creativity and scholarly rigour. 

What's hot in organic chemistry? 

Complexity. It is very exciting to see how organic chemistry is targetting increasing levels of complexity in all areas of organic and bioorganic research: complex molecular and supramolecular architectures; remarkable transformations involving many bond breaking and making steps; unique chemical processes that produce no waste and require no purification; multistep synthesis on a chip; the effects of organic molecules on intricate biological processes - the list goes on and on. 

What are the best and worst bits about your job? 

The best part of my job is that I get to work with some of the brightest and most enthusiastic young scientists in the world. We share the craziest ideas, dream up and make the most beautiful molecules, test them, share our thoughts and results with the community (for example, by publishing in OBC), and then we get to start all over again. I also enjoy teaching students at all levels. The worst part our job is that there is never enough time to do everything we want to. 

What would you be if you weren't a scientist? 

Unfortunately, a professional football player was always out of the question. I guess I could have been an archaeologist. Being a descendent of the P'urhépecha people of central Mexico, I have always been fascinated by the art and technologies of the many prehispanic cultures of America.